Lens.



i No. vergaan.V f Y y photographic negatives.

ULEIOHNEHRING, OE NEW YORK', N. Y., AssieNoR rro THE SCIENTIFIC LENS-co., OE NEW YORK, N. y., A CORPORATION OE NEW YORK LENS'.

` SPECIFICATION forming part i refuges Patent No. 756,881, dated p1-nagaan p appesa@ ma mma-y s, 1904. emu no, islam. un man.)

To all whom it my concern.-

Be it known that I, ULRICH NEHRING, a citizen ofthe United States. residing in New York, in the county of New York andState of New York, have invented certain new and useful Improvements in Lenses, of which the following is a specification.

The present invention` relates to lenses, and more particularly to lenses used in producing Itis swell-known fact inthe art of photog- 'raphy that lenses are subject to spherical and chromatic aberration, producing a di'erence in the 'focal distance between the edge rays of a lens and the center rays and between the more refrangible violet rays and the less refrangible red rays.. These defects become .epparent in photography by causing dierentliv sharp er distorted picturesor by notlgivving a .true record of the correct color value of the "orlglnal object.

It has been tried heretofore to overcome these defects for the production of evenly-sharp pictures by moving the entire photographic lens or lens system to and from the sensitive surfaceduring the time of exposure.

The present invention has for its object to Y accomplish this effect bfnging the focal dafnceof a lens or n insteadjfi npjgngtwliefentirelens toQand from the sensi'- tive surface; and nit consists'ofthe construe-tion illustrated in the accompanying drawings, in which Figure 1 is a side View, partly in section, of a photographic lens; Fig. 2, a cross-section of the same in the lihe A A of Fig. l, and Figs.

3 and 4: similar views as Fig. 1 of several modifications.

In more fully describing the underlying invention .it is well to keep in mind that the fo-v cus of a lens is that point in the Optical axis of the lens in which parallel rays meet after emergence and that' the focal distance of a lens is the distance between the focus and the optical center of the lens. The equivalent focus of a lens system is that point in the optical axis of a series or plurality of lenses in which parallel. rays meet-'after passing all the s and operates to prevent a sudden movement of UNIT@ STATES YPTENT @FICE distance between 'the equivalenifocusand the 5v optical center of a theoretical or phantom lens .or lens-board of a photografhic camera. Se-v -the outer casing.V A suitable space is pro -rneans may be adapted to operate by expan- 7cJ 'sion as well as by contraction. The coiled Patented .april 12,1901;

lenses, and equivalent focal distance theV representing the joint action of the whole se-- ries or plurality of lenses -forming the systeme;-

In the drawings forming part of the present application, l is the ordinary front board s cured to the saine by alens-ring or other means is the outer casing 2 of the lens, which carries one lens or lens set, forming a part of the entire system. 3 is the inner casing, car- 6@ rying another lens or lens set and telescopingvided between the two casings for receiving an elastic or resilient means, such as afcoiledm spring 4, Figs. 1 and 3, which when operat- 65 ing cause a change of the distance between Ath e lenses ,o r l ens se t sV forming th e` systern .and

therefore, a change of the focal distance.

It is to be understood that the resilient spring 4, for instance, when used inthe device illustrated in Fig. l may first be compressed and then act on the lens-carrying casings by expansion, thereby lessening the distance between the lenses, and consequently changing the focal distance of the system, It is to be understood that the resilient means. If the same spring is fastened to the lens-casings and first expanded, it will act by contraction, and thereby increase the distance between the lenses. 'Theseelastic or resilient means may be located between the lenses, es shown' in the drawings, or they may be outside of one or the other lens.

Fig. 4 illustrates a device operated by xiieans of a mediumsuch as air, oil, glycerin, ':c.'-which is pressed into or rcmovedfrom u suitable space 8 between the lens-casings, and thereby 'causing a variation between the 90 lens distance and a corresponding variation of the focal distance. A packing 5, consistiuv' of a leather washer, preferably impregnatc with oil or glycerin or other means, forms a nearly air-tight closure between the casings I the casing released relatively the other cas- Same.

the other in connection with a suitable poiver device for Working the rack and pinion.

ln using. the device the release 6 is set into such a tooth 7 as to cause when released 'the desired change of the distance between the lenses and the corresponding change of the lens moves gradually without jerking towardA The method of employing equivalent focal-distance. Taking', for instance, the device illustrated in Fig. 1, the front lens is pulled out a short distance and the coiled spring-.thereby eXpanded. The re lease 6 isset, for instance, in the first tooth. The object to be'pliotographed is then focused in the ordinary waigaud the-shutter, which may be operated by the same bulb as the release 6, is opened, and during the time or duratienof the photographic exposure one or from the other lens, whereby the distance between the lenses is varied, causing a correspending change of the i"'ocaldistance or .equivalent focalvdis'tance of the lens or lens s 'stein and producing a' photographic negative of even sharpness and without distortion` and giving a true record of the color values of the original object.

the underlying invention has alreadybeen set forth in the copending application for Letters Patent, Serial No. ljled February 4, i90-l Vi'hat is claimed as new and useful, and desired to be secured by United States Letters Fatent, is-- 1. The combination with a lens, of means for changing the i'jocal distance of the leas during the time of exposure.

2.-'The combination with a lens, of means for gradually changing 'the focal distance of the lens during the time of exposure.-

3. The combination with' a plurality of lenses, of means for changing the equivalent focal distance of the lenses during the time of exposure.` L

4.' The combination with a plurality of lenses, lof .'neaiis' for `gradually changing the equivalent focal distance of' tlielenses, during the time of exposure.

5. The combination with a plurality of lenses, of means for changing the location of the focus of one lens or lens set relatively to of exposure.

'of elastic or res .distance between the the location of the focus of another lens or l lenses, of means for gradually changing the lens or lens set location of the focus of one *cation of the focus relatively to thelocation-of the focus of another lens or lexis set during the time 'of exposare.

't'. The coinlziation with a plurality of lenses, of elastic or resilient means for chang- 70 ing tbe location of the focus of one lens' or lens set relatively to the location of the focus of ther lens cfr lens-set during the time of exposure. n

S. The comhrzation with a Vplurality of 75 lenses, of means -or gradually changing the 55 distance. betweeraalielensesduring the time Il- The cornhziaiion with a lens System 'comprising a plurality of lenses or lens sets` lenses during the time of exposure. la

12. The combination withfa lens syst/en:- coinprising plc ality of lenses' or lens sets, of-elastie or res 'changing the 'dist gneoez ce between theleiisesduri3. l lie-"corali" ioi';\"`\`vith a lens' of means l p l forcaanging the i zal distance of thelens durt of the change. ation with a leus,- of mean ing the focal distance of c time of exposure, and the amounto t-he change. V^ tion'with a plurality of or changing the equivalent for gradually c the lens durir'ff ineansoradju l5- The cozr. lenses. of means '.nt means' for changing the 9 nient means for graduzivllylJgS- focal distance et' the lenses durinfr tlietiine of exposure, and rneatns for adjusting theamount of the change.

15. The comb-I tion with a plurality of lenses, of means er grad ally changing the eqnialent foe: nce ofthe lenses during the time of 'expos re, and means for adjusting the amount c 1he change.

l?. The corr' tion with a plurality of lenses, of means u cation of'the focus onelens or lens set relatively to the loe en of the focus of another lens or lens set, e :l means for adjusting the amount of the c. ge.,

The cozni ation `with a plurality of lenses. of mear r changing the location of the focus of one s orlens set relatively to the location of tbe focus of another lens or lens set during theinie of exposure,and means for aujusting the mount of change.

19. VDie 'cornP lenses, of meansi -r gradually changing the loof one lens or lens set rela- IIO Tradually changing the lof;

ation with a plurality of A 'tivelyto the location of tbe focus of another lens or len's setduring the time of exposure,

and means for adjusting the amount of the chauffe. 20. Theeombination with a plurality of lenses, of elast-ic or resilient means for changing the location of the focus of one lens er lens set relatively to the location of the focus of another lens or lens set during the time of exp'osure", und means for adjusting the amount of the change.

' 21. The combination with a. pluralityfof i lenses, of elastic or resilient means for gradually changing tli'e location of tl'iefocii's of one ls or'lens set relatively to theglocationpf tbe focus of anotler lensoi' lons set during `the:

time of exp'sure, and means for adjusting the 'amount of the change.

22. The combination with a 'plurality of, lenses, of means for changing tbe distance between the lenses during` the time of exposure, and means for adjusting theamount of change. 23. The combination with" a. plurality of lenses, of means f 'or gradually changing the distance between the lenses during the time of exposure, and means for adjusting the amount of the change.

24. The combination with a plural-ityv of lenses, of elastic or resilient means forchanging the distaneebetiveen the lenses dui-ing theV time of exposure, and means for adjusting the amount of change.

25. The combination with a plurality of lenses, of elastie or resilient means for gradu- 'ally changing'the distance between the lenses during the time of exposure, and means for adjusting the amount of the change.

A 26. The combination with aplurality of l lenses pr lens sets,'of a easing for each lens or lens set, one casing sur! ounding theother and 4 lenses or lens sets, of a easing for each lens oi' Tiens set and telescoping eaeh'other, means for eausing a'gradual movement ei one of the casingsiduring the time of exposure, and means A'for adjusting the' amount of the movement.

29. The combination with a plurality of lens set, one easngtelescoping the other and slidable therein, elastic or resilient means for g; causing said movementduring the time of exof said movement.'

30. The combination -ivith ,aljilurality of .lenses or lens sets, of a easing for each lens or -lens set, ouecasing telescoping the other and movable: therein, elastie'or resilient means for lcausing gradually said' movement du ing the amount of said movement.

Signed at New York, in the county of New February, 1904.

ULRICH NEHRING.

In presence ofi i JOHN O. Si-irrnizr,

i Annan PIXKERTON.

'lenses or lens sets, of a casing for each lens or if posure, and means for adjusting the amount 'Ork and Siate of New York, this 1st day of' 28. The combination with a plurality of 'l time of exposure, and means for udjus ing the Y 

